The present invention relates to a method for extracting vegetable oils from oleaginous plants.
The methods currently used to extract vegetable oils entail the use of solvents both during primary extraction processes, in the case of seeds or caryopsides of oleaginous plants which do not release the oil contained therein by simple pressing (for example cotton, maize, soya, rape etcetera) and, in the case of oleaginous plants which can be pressed, such as olives, sunflowers and peanuts, during the secondary step for the extraction of oil from the plant residues that remain after pressing.
Oleaginous seeds generally contain the lipids to be extracted in the internal cytosol, which is enclosed externally by the cuticle with its integument constituted by macromolecules.
Research conducted on the various protective integuments allows to say that said integuments are usually constituted by sugary polymers and particularly by the following polysaccharides: hemicelluloses, celluloses, inulins, starches and pectins. These polymers are in turn accompanied by a waxy cuticle which is constituted by saponins and phospholipids; ligneous seeds are of course an exception.
The mechanism by which the solvent is able to extract the oil from the cytosol is due to a factor related to osmosis and to the dissolution of saponins and phospholipids, so that the solvent creates a breach in the integument through which it flows into the cytosol.
The use of solvents certainly entails evident disadvantages, especially from the point of view of the possible risks for human health, particularly in the case of combustible oils for food use.